Implant method and implanter by using a variable aperture

ABSTRACT

A variable aperture within an aperture device is used to shape the ion beam before the substrate is implanted by shaped ion beam, especially to finally shape the ion beam in a position right in front of the substrate. Hence, different portions of a substrate, or different substrates, can be implanted respectively by different shaped ion beams without going through using multiple fixed apertures or retuning the ion beam each time. In other words, different implantations may be achieved respectively by customized ion beams without high cost (use multiple fixed aperture devices) and complex operation (retuning the ion beam each time). Moreover, the beam tune process for acquiring a specific ion beam to be implanted may be accelerated, to be faster than using multiple fixed aperture(s) and/or retuning the ion beam each time, because the adjustment of the variable aperture may be achieved simply by mechanical operation.

FIELD OF THE INVENTION

The invention generally relates to an implant method and an implanterfor implanting substrate, and more particularly relates to a method andan implanter capable of implanting different portions of one or moresubstrate by using different customized ion beams shaped respectively bya variable aperture located right in front of the one or more substrate.

DESCRIPTION OF THE RELATED ART

In general, as shown in FIG. 1A, an implanter has at least an ion source101 and an analysis magnet 102. An ion beam 103 is generated by the ionsource 101 and then analyzed by the analysis magnet 102 to screen outthe ions with un-desired charge-mass ratio(s). After that, the ion beam103 is implanted into a substrate 104 (such as a wafer or a panel). Asusual, the quality of the ion beam 103 outputted from the analysismagnet 102 is not good enough for efficiently implanting the substrate104. For example, the ion beam current distribution on the cross sectionof the ion beam 103 may be undulant or have a long tail. Then, theimplantation of the ion beam 103 on the substrate 104 may be non-uniformif no extra step/device is used to improve the distribution of implantedions (or atoms and/or molecules) in the substrate 104. For example, itis common that in certain beam current and/or energy range for a givenspecies of ion beam 103, the beam shape, size or cross section fallsshort from the spec requirements. Then, the dose distribution controlfor one or more dose regions on the substrate 104 can not be optimized.For example, for dose split or other non-uniform implantation, differentportions of the substrate 104 require different doses. Then, even thequalify of a fixed ion beam 103 is well qualified for one dose region,different portions still have to be implanted differently for providingdifferent doses by using the fixed ion beam 103. Note that this is truefor both types of beams typically used, the spot ion beam and the ribbonion beam.

One prior art, as shown in FIG. 1B, improves these disadvantages byusing the magnet assembly 105 to further enhance the beam optics formodifying (deforming, collimating and/or deflecting) the beam 103 in aposition between the analysis magnet 102 and the substrate 104. Asusual, the magnet assembly 105 has one or more magnet, where each magnetmay provide a uniform or non-uniform magnetic field. However, thedetails of the magnet assembly 105 are not limited. Herein, as anexample, the magnet assembly 105 is located around the trajectory of theion beam 103, such that the motion of each ion of the ion beam 103 isdirectly modified by the magnetic field generated by the magnet assembly105. Hence, by properly adjusting the operation of the magnet assembly105, such as adjusting the current applied to the magnets or adjustingthe relative geometric relations among different magnets, the ion beam103 is correspondingly modified and then the projected area of the ionbeam 103 on the substrate 104 can be correspondingly adjusted. However,the cost of the magnet assembly 105 is high, the precise adjustment ofthe magnetic filed is difficult, and the process of modifying ion beamby the magnetic filed is complex and time consuming.

Another prior art, not shown in any figure, improves these disadvantagesby adjusting the operation of the ion source 101 and/or the analysismagnet 102, such that the ion beam 103 outputted from the analysismagnet 102 may be modified well. However, the cost is high and theoperation is complex, and the room for adjustment of the ion beam 103 islimited. The other prior art, not shown in any figure, improves thesedisadvantages by adjusting the scan parameter(s), such as scan pathpitch and the scan speed, such that different implantation aredifferently achieved by the same ion beam 103. Similar, the cost and theoperation still is high and complex, and the room for adjustment of thescan parameter(s) is limited.

Still one prior art, as shown in FIG. 1C, improves these disadvantagesby using an aperture device 106 with a fixed aperture 107 to shape theion beam 103 before the substrate 104 in implanted by the shaped ionbeam 103. Reasonably, by properly choosing the fixed aperture 107, theion beam 103 can be shaped without modifying the ion beam 103 itself. Inother words, the prior art does not need to further modify the ion beam103 outputted from the analysis magnet 102 by any magnetic/electricfiled and also does not need to adjust the operation of the ion source101 and/or the analysis magnet 102. In addition, the fixed aperture onlycan shape the ion beam 103 but can not adjust the ion beam 103, such asadjusting the ion beam current distribution on the cross section of theion beam 103. Hence, another prior art as shown in FIG. 1D positions thefixed aperture 107 within the aperture device 106 at an end of a beamoptics and right in front of the substrate 104. Hence, after the ionbeam 103 is modified by the beam optics, the ion beam 103 can be furthershaped by the fixed aperture 107 again to achieve better shape ofprojected area of the ion beam 103 on the substrate 102. In other words,by using the fixed aperture 107, the required adjustment of the ion beam103 provided by the beam optics can be less strict than the requiredadjustment of the ion beam provided by the beam optics without using anyaperture. However, the two prior arts have a major disadvantage: lack offlexibility. The shape and the size of a fixed aperture 107 is fixed,and then the room for adjusting of the shaped ion beam 103 is finiteeven the overlap between the ion beam 103 and the fixed aperture 107 ischanged by shifting the aperture device 106 aperture device along adirection vertical to the ion beam 103 and/or rotating the aperturedevice 106 around another direction in three-dimensional space atintersecting of the ion beam 103 through a tilt or twist mechanism.Hence, multiple aperture devices 106 with different fixed apertures 107are required and then the implantation on one or more substrate 104 maybe interrupted several times for substituting the multiple aperturedevices 106 to use different fixed apertures 107 for achieving differentimplantations.

Accordingly, it is still desirable to develop different approach toimprove the above disadvantages, especially to develop a simple andcheap approach.

SUMMARY OF THE INVENTION

The present invention is directed to an implant method and an implantercapable of shaping an ion beam before a substrate is implanted by theshaped ion beam. Herein, an aperture device with a variable aperture isused to shape the ion beam, such that the shape and/or the size of theion beam is confined and modified by the variable aperture. Therefore,different shaped ion beams can be differently provided by simplyadjusting the variable aperture, even further by shifting, tiltingand/or twisting the variable aperture. In other words, the flexibilityof the proposed variable aperture is significantly high.

Some potential applications of the proposed variable aperture arerelated to the optimization of the implantation of a substrate. Herein,the variable aperture is flexibly adjusted so let both the size and theshape of the projected area of an shaped ion beam on the substrate(s),even the quality of the shaped ion beam, is optimized. For example, thevariable aperture can be flexibly adjusted to implant different doseregions with different shaped ion beams without re-tuning the ion beamor replacing the hardware used to adjust the ion beam. Another potentialapplication of the present invention is to flexibly adjust the variableaperture according to an ion beam current distribution on the crosssection of the ion beam, such that only a desired portion of the ionbeam is implanted into the substrate. Herein, the desired portion may bea constant-value-like central portion or a Gaussian-distribution-likecentral portion. For example, when the ion beam has a long tail, i.e.long tail on its cross section, it is optional to flexibly adjust thevariable aperture to properly cut off the long tail such that thecontrol of the implantation on substrate is not affected by the longtail. The other potential application of the proposed variable apertureis to flexibly adjust the variable aperture to shape the ion beam forimplanting each dose region on the substrate according to at least oneof the following: a required dose of the dose region, a shape of thedose region, and a size of said dose region. Reasonably, the potentialapplication is more suitable for the dose split, because differentshaped ion beams required to implant different dose regions may beefficiently acquired by only adjusting the variable aperture. Still afurther potential application of the present invention is to acceleratethe beam tune process for providing different ion beams to achievedifferent implantations on one or more substrate. Initially, the ionbeam generated by the ion source is modified by a beam optics (such asthe analysis magnet and the magnet assembly), such that at least aspecific portion of the cross section of the ion beam has good enoughquality. Then, by flexibly adjusting the variable aperture, the specificportion of the ion beam may be separately shaped to form the requireddifferent ion beams without amending the ion beam itself.

One embodiment of the present invention is an implant method forimplanting a substrate. Initially, provide an ion beam and a substrate.Then, adjust a variable aperture within an aperture device, such thatthe substrate is implanted by a shaped ion beam shaped by the variableaperture. Herein, one or more of size and shape of the variable apertureis adjustable. To enhance the efficiency, the variable aperture withinthe aperture device is positioned at end of a beam optics and right infront the substrate. Hence, after the current distribution on the crosssection of the ion beam is tuned well by the beam optics, the ion beammay be shaped simply by only adjusting the variable aperture withoutfurther adjustment on the beam optics. Optionally, the variable apertureis adjusted after the substrate is implanted and before a differentsubstrate is implanted, such that different substrates are implanted bydifferent shaped ion beams. Optionally, the variable aperture isadjusted at least twice during an implantation on a substrate, such thatdifferent portions of the substrate are implanted by different shapedion beams.

Another embodiment of the present invention is an implant method forimplanting a substrate. Initially, provide an ion beam and a substrate.Then, shape the ion beam by a variable aperture within an aperturedevice before the substrate is implanted by the shaped ion beam, whereinone or more of size and shape of the variable aperture can be flexiblyadjustable. Herein, to enhance the efficiency, the variable aperturewithin the aperture device is positioned at an end of a beam optics andright in front of the substrate. Hence, after the current distributionon the cross section of the ion beam is tuned well by the beam optics,the ion beam may be shaped simply by only adjusting the variableaperture without further adjustment on the beam optics. Optionally, thevariable aperture is adjusted after the substrate is implanted andbefore a different substrate is implanted, such that the differentsubstrates are implanted by different shaped ion beams. Optionally, thevariable aperture is adjusted at least twice during an implantation on asubstrate, such that different portions of the substrate are implantedby different shaped ion beams.

Note that the invention does not limit the mechanical design of theaperture device with the variable aperture. For example, it can be somemovable plates that each has an opening, or a combination of a fixedplate having an opening and a movable plate without any opening.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A to FIG. 1D respectively schematically illustrates the essentialmechanism of some conventional implanters.

FIG. 2A to FIG. 2B schematically illustrates the essential mechanism ofan implanter according to two embodiments of the present invention

FIG. 2C to FIG. 2E illustrate how different shaped ion beams aregenerated and a corresponding flowchart according to the usage of theconventional fixed aperture.

FIG. 2F to FIG. 2H illustrate how different shaped ion beams aregenerated and a corresponding flowchart according to one embodiment ofthe present invention.

FIG. 3A to FIG. 3B respectively illustrates an implant method accordingto two embodiment of the present invention.

FIG. 4A to FIG. 4C illustrate schematic views for showing how thepractical ion beam current distribution of an ion beam to be implantedinto a substrate is amended according to one embodiment of the presentinvention.

FIG. 5 illustrates a schematic view for showing how the dose splitsituation is properly achieved according to one embodiment of thepresent invention.

FIG. 6A to FIG. 6D illustrates a schematic view for showing how the beamtune process is accelerated according to one embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in details to specific embodiments of thepresent invention. Examples of these embodiments are illustrated in theaccompanying drawings. While the invention will be described inconjunction with these specific embodiments, it will be understood thatthe intent is not to limit the invention to these embodiments. In fact,it is intended to cover alternatives, modifications, and equivalents asmay be included within the spirit and scope of the invention as definedby the appended claims. In the following description, numerous specificdetails are set forth in order to provide a thorough understanding ofthe present invention. The present invention may be practiced without atleast one of these specific details. In other instances, the well-knownprocess operation is not described in detail in order not to obscure thepresent invention.

FIG. 2A schematically illustrates the essential mechanism of animplanter in accordance with one embodiment of this invention. Herein,the ion source 201 generates the ion beam 203 and the analysis magnet202 screens out the ions with un-desired charge-to-mass ratios from theion beam 203. Both the ion source 201 and the analysis magnet 202 may beviewed as an ion beam generation assembly. Before the substrate 204 isimplanted, the ion beam 203 is shaped by the variable aperture 207within the aperture device 206, such that one or more of shape and sizeof the ion beam 203 implanted into the substrate 204 (such as wafer andpanel) can be different than that of the ion beam 203 just outputtedfrom the analysis magnet 202. By comparing FIG. 2A with FIG. 1C, onemain characteristic of the embodiment is the variable aperture 207. Inthe prior art, both the shape and the size of the fixed aperture 107 arefixed, and then the cross section of the shaped ion beam 103 also has afixed shape and size. In contrast, in the embodiment, both the shape andthe size of the variable aperture 207 may be variable among a range.Hence, both the shape and the size of the cross section of the shapedion beam 203 also may be variable among the range. Herein, both theshape and the size of the variable aperture 207 are not particularlylimited. For example, the shape of the variable aperture 107 can beoval, ellipse, circle or other contour capable of ensuring smooth ionbeam current distribution of the shaped ion beam. Moreover, to enhancethe efficiency of acquiring required ion beam, as the embodiment shownin FIG. 2B, the variable aperture 207 within the aperture device 206 islocated right in front of the substrate 204 and at and end of the beamoptics (such as the combination of the analysis magnet 202 and themagnet assembly 205). Herein, the details of the beam optics 205 areomitted because it may be any well-known beam optics. Furthermore, theaperture device 206 can be shifted along a direction vertical to the ionbeam 103 and/or rotated around another direction in three-dimensionalspace at intersecting of the ion beam 103 through a tilt and/or twistmechanism, such that the overlap between the ion beam 103 and thevariable aperture 207 may be further changed and then the room foradjustment of the shaped ion beam is increased. Note that theshift/tilt/twist mechanism of the aperture device 206 can be equal tothe shift/tilt/twist mechanism of the aperture device 106, and then therelated details are not discussed hereinafter.

FIG. 2C to FIG. 2E shows how to use the conventional fixed aperture asshown in FIG. 1C and FIG. 1D to implant different dose regions withdifferent shaped ion beams, and FIG. 2F to FIG. 2H shows how to use theproposed variable aperture to implant different dose regions withdifferent shaped ion beams. As shown in FIG. 2C and FIG. 2D, differentaperture devices 1061/1062 with different fixed apertures 1071/1072 areseparately used to shape the same ion beam 103 for forming differentshaped ion beams to separately implant different dose regions, such asdifferent portions of the substrate 104. The corresponding method isshown in FIG. 2E. Herein, a key step is the block 212 that replace afirst aperture device with a first fixed aperture by a second aperturedevice with a second fixed aperture, which is different than the firstfixed aperture. In contrast, as the embodiment shown in FIG. 2F and FIG.2G, one and only one aperture device 206 with a variable aperture 207 isused to shape the same ion beam 103 for forming different shaped ionbeams to separately implant different dose regions, such as differentportions of the substrate 204. The corresponding method is shown in FIG.2H. Herein, a key step is the block 215 where the aperture device 206 isadjusted such that one or more of size and shape of the variableaperture 207 is adjusted. Of course, the key is how to provide differentshaped ion beams for implanting different dose regions but not how thedose regions are distributed. In other words, the embodiment shown inFIG. 2E to FIG. 2H can be expanded to cover the case that differentsubstrates 204 have different required doses but each substrate 204 hasone and only one dose region.

The proposed variable aperture also may be used to accelerate the beamtune process. For example, different but similar shaped ion beams may berequired to implant different lots of substrates, such that differentsubstrates may have different uniform doses. In such situation, after anoriginal ion beam is acquired by properly adjusting the beam optics, thedifferent shaped ion beams may be separately acquired by repeatedlyadjusting the variable aperture. Initially, the variable aperture is setto have a first shape and a first size so let a first shaped ion beammay be generated by using the variable aperture to shape the originalion beam. Then, after some substrates having a first dose are allimplanted, the variable aperture is adjusted to have a second shape anda second size so let a second shaped ion beam may be generated by theadjusted variable aperture to shape the same original ion beam. Byrepeating the above steps, different substrates having different dosesmay be implanted by only adjusting the variable aperture to separatelyshape the original ion beam. In other words, the beam optics, even theion source, needs not be repeatedly adjusted to provide different ionbeams for implanting different substrates with different doses. Also,need not to exchange the aperture device with the variable apertureduring a period of implanting different substrates with different doses.Accordingly, the beam tune process is accelerated and faster than otherbeam tune process using the above prior arts.

Reasonably, to achieve the same room of adjustment on the shaped ionbeam, an aperture device 206 with a variable aperture 207 can replacesome aperture devices 106 that each has an individual fixed aperture107, and then both the total hardware cost is reduced and theflexibility of adjusting the shaped ion beam is increased. Also, thestep of replacing multiple aperture devices 106 with different fixedapertures 107 is replaced by the step of adjusting a variable aperture206 with an aperture device 207, and then the time consumption used toprovide different shaped ion beam is reduced. Moreover, as usual, thesedifferent aperture devices 106 are stored outside the implanter chamberfor reducing the chamber size, and then both the vacuum venting processand the vacuum pumping process are desired for replacing differentaperture devices 106. In contrast, the adjustment of an aperture device206 located inside the implanter chamber can be achieved without anyvacuum venting process or any vacuum pumping process. Hence, theoperation is simplified and the risk of contamination is reduced

Other embodiments include two methods for implanting a substrate, asshown in FIG. 3A and FIG. 3B. In the former embodiment, as shown inblock 301, provide an ion beam and a substrate; and as shown in block302, adjust a variable aperture within an aperture device, such that thesubstrate is implanted by a shaped ion beam shaped by the variableaperture. One main character of this embodiment is the step of adjustingthe variable aperture. In the latter embodiment, as shown in block 303,provide an ion beam and a substrate; and as shown in block 304, shapethe ion beam by a variable aperture within an aperture device before thesubstrate is implanted by the shaped ion beam, wherein one or more ofsize and shape of the variable aperture is flexibly adjustable. One maincharacter of the embodiment is the limitation “one or more of size andshape of the variable aperture is flexibly adjustable”. Moreover, forboth embodiments, the variable aperture can be adjusted again after thesubstrate has been completed implanted and before another substrate isimplanted. Hence, different substrates can be implanted by differentshaped ion beams in sequence. Similarly, for both embodiments, thevariable aperture can be adjusted at least twice during the implantationof the substrate. Hence, different portions of the substrate can beimplanted by different shaped ion beams.

One more embodiment is a potential application of the proposed variableaperture. As shown in FIG. 4A, an ideal ion beam current distribution ona cross section of the ion beam may be a symmetric curve which has asmooth and non-undulant portion and a short tail locating on the edge ofthe smooth and non-undulant portion Herein, the term “smooth andnon-undulant portion” is more generally referring to a beam profileleading to more uniform dose distribution after one or more scans on thesubstrate, when the scan parameter may be adjusted accordingly. However,in the practical world, as shown in FIG. 4B, the real ion beam currentdistribution on the cross section of the ion beam may be asymmetricaland/or or may have a long tail. The differences between the practicaldistribution and the ideal distribution usually are proportional to thesize of the ion beam, and usually are distributed on the edge of the ionbeam current distribution. The difference between the practicaldistribution and the ideal distribution also may be time dependent andmay be different for different required ion beam currents and ion beamvoltages. Therefore, as shown in FIG. 4C, by using the proposed aperturedevice 206 with variable aperture 207, the ion beam can be flexibly andefficiently shaped so that the quality of shaped ion beam almost is notaffected by the differences between the ideal ion beam currentdistribution and the practical ion beam current distribution. Forexample, after the practical ion beam current distribution is detectedby a beam profiler, the variable aperture may be flexibly adjusted tohave a specific size and a specific shape corresponding to a requiredsmooth and non-undulant portion of the practical ion beam currentdistribution. The, by using the adjusted variable aperture to shape theion beam, essentially only the required portion of the practical ionbeam will be used to implant the substrate. Note that FIG. 4C only is anidea figure where both the size and the shape of the shaped ion beam areperfectly equal to that of the adjusted variable aperture 207. Indeed,owing to at least the space charge effect, the size and the shape of theprojected area of the shaped ion beam on the substrate should bedifferent than the size and shape of the adjusted variable aperture 207.However, owing to the variable aperture 207 usually is positioned veryclose to the substrate, the effect of the variable aperture 207essentially is not degraded by it.

Another embodiment also is a potential application of this proposedvariable aperture. The potential application is related to the “dosesplit”, especially is related to the situation that different doseregions on same substrate requires different doses. As shown in FIG. 5,two dose regions 501/502 with different sizes/shapes are separatelylocated on the substrate 500. Then, by using the aperture device 206with the variable aperture 207, two shaped ion beams are respectivelyused to implant the two dose regions 501/502. For the situation that thetwo dose regions 501/502 require different doses, the two shaped ionbeams will have different sizes (different lengths and/or differentwidths). Clearly, the projected areas of the different shaped ion beamson the substrate 500 will have different size, and then the implantedarea of the different shaped ion beams will be different even thedifferent shaped ion beams are moved along same scan path with same scanspeed. The wider the shaped ion beam is, the larger the implanted areais. Therefore, even the scan parameters' values (such as the scan pathand the scan speed) are uniformly distributed over the substrate 500 (atleast uniformly distributed over the dose regions 501/502), the two doseregions 501/502 will have different doses after both the dose regions501/502 are thoroughly scanned by the different shaped ion beamsrespectively.

Still another embodiment also is a potential application of the proposedvariable aperture. In FIG. 5, the shape of each of dose regions 501/502is simple and regular. However, sometimes, the dose regions may haveirregular shapes. For example, a former deposition process may beimperfectly proceeded and then a deposited film with non-uniformthickness is formed on a substrate. Note that the etching rate of thedeposited film may be changed if the quality of the deposited film ischanged by implanted atoms/molecules/ions. Hence, a non-uniformimplanting process may be performed to non-uniformly change the qualityof the deposited film before a latter uniform etching process isperformed. Herein, the higher the thickness of a portion of thedeposited layer is, the lower the implant dose in this portion of thedeposited layer is. Therefore, one advantage of this embodiment issignificant. The shape/size of the variable aperture can be continuouslyadjusted during a period of scanning an ion beam through a substrate,such that the shaped ion beam can be continuously adjusted to fit theshape of different dose regions corresponding different portions of thenon-uniform deposited film.

Further, another embodiment is related to how to accelerate the beamtune process by the proposed variable aperture as shown in FIG. 6A toFIG. 6D. Initially, as shown in FIG. 6A, an original ion beam 600 and avariable aperture 61 within an aperture device 62 are provided. Herein,the original ion beam 600 is outputted from an analysis magnet and hasoriginal ion beam current distribution 641 on the cross section of theoriginal ion beam 600, which may be measured by using a beam profiler.Then, as shown in FIG. 6B, the original ion beam 600 is further modifiedby using a manage assembly 65 which is a portion of a beam optics, evenby changing the operation of an ion source. Hence, an amended ion beamcurrent distribution 642 on the cross section of the modified ion beam601 is acquired. Herein, the amended ion beam current distribution 642is smoother and less undulant than the original ion beam currentdistribution 641, and essentially has a desired central portion and asurrounding tail. Herein, the desired portion may be aconstant-value-like central portion or a Gaussian-distribution-likecentral portion. As usual, one or more of the shape and the size of themodified ion beam 601 is different that of the original ion beam 600.Next, as shown in FIG. 6C, the aperture device 62 is adjusted so thatthe variable aperture 61 is smaller than or equal to the desired centralportion. Finally, as shown in FIG. 6D, the modified ion beam 601 isshaped by the adjusted variable aperture 61 within the aperture device62, so as to let a shaped ion beam 602 with good ion beam currentdistribution 643 on its cross section be implanted into a substrate.Accordingly, by using the proposed variable aperture 61, the beam tuneprocess may be simplified into two steps. In the first step, the ionbeam 60 is briefly modified by the beam optics to have at least adesired portion. In the second step, the variable aperture 61 isflexibly adjusted to only allow the desired central portion become ashaped ion beam 602 to be finally implanted into the substrate 66.Reasonably, when beam optics are used to only briefly modify theoriginal ion beam 600 but not directly acquire the final shaped ion beam602, the modification of the beam optics is significantly simplified.Not only may time consumption of the adjustment of the beam optics bereduced, but also the required adjustment preciseness of the beam opticsmay be simplified. Besides, to compare the prior art of using the fixedaperture, a variable aperture 61 can support a large room for adjustmentof the ion beam 103. Thus, not only the cost of multiple fixed aperturesmay be saved, but also the time consumption and potential contaminationduring the step of replacing different fixed aperture may be reduced.Thus, the beam tune process is significantly accelerated by the usage ofthe variable aperture.

In addition, the proposed variable aperture can be used to flexiblyshape the ion beam, no matter whether it is spot ion beam or a ribbonion beam. The aperture device will block partial ion beam and allowpartial ion beam to pass through the variable aperture. Herein, to avoidpotential contamination and overcome the high temperature issue raisedby the collision between the ion beam and the aperture device, thematerial of the aperture device usually is graphite. Moreover, tofurther improve the quality of the implantation by using the presentvariable aperture, it is optional to adjust the variable aperture whenthe ion beam is not projected on the substrate, such that the substratewill be implanted by only properly adjusted shaped ion beam(s). In otherwords, during a period of adjusting the variable aperture, the ion beamand/or the substrate may be parked. For example, the substrate may beparked when the substrate is at position not seeing the ion beam, suchas parking the substrate at a scan turn around point when the ion beamis tuning or the variable aperture is adjusted. For example, the ionbeam may be parked by turning off the analysis magnet or suppressinglanding of the ion beam where there is cooling, especially when a longduration is expected.

Note that both the magnetic field and/or the electric field areefficient to modify an ion beam, no matter to the change the shape ofthe ion beam to change the ion beam current distribution on the crosssection of the ion beam. Hence, it is popular to use the beam optics tomodify the ion beam firstly, and then to use the variable aperturewithin the aperture device in shape the modified ion beam in sequence.However, the potential applications of the proposed variable aperturemay be independent on the usage of the beam optics, and also thecharacteristic of the proposed variable aperture is not limited by otherportions of the beam optics.

Furthermore, the invention never limits the details of the mechanicaldesign of the aperture device 206 and the variable aperture 207. Forexample, the aperture device 206 can have some movable plates where eachhas an opening. Hence, the overlap of these openings can form thevariable aperture 207, and the relative movement among these movableplates can adjust one or more of size and shape of the overlap (i.e. oneor more of size and shape of the variable aperture 207). For examples,the aperture device 206 may be some plates capable of moving relative toeach other, a combination of a fixed plate and a movable plate whereeach plate has a hole, or a combination of four plates where two ismovable along X-direction and another two is movable along Y-direction.Hence, the variable aperture can be adjusted by modifying a relativegeometric relation among one or more plates used to define the variableaperture, or by moving one or more plates used to define said variableaperture.

Variations of the method and the implanter as described above may berealized by one skilled in the art. Although the method and theimplanted have been described relative to specific embodiments thereof,the invention is not so limited. Many additional changes in theembodiments described and/or illustrated can be made by those skilled inthe art. Accordingly, it will be understood that the present inventionis not to be limited to the embodiments disclosed herein, can includepractices other than specifically described, and is to be interpreted asbroadly as allowed under the law.

What is claimed is:
 1. A method of implanting ions onto a substrateusing an ion beam and a variable aperture, the method comprising:obtaining a substrate, the substrate having non-uniform properties dueto a previous deposition process; determining, by an ion implantingdevice, a first ion beam parameter for a first portion of the substrateand a different second ion beam parameter for a different second portionof the substrate in response to the non-uniform properties of the firstportion and the properties of the second portion, respectively;producing the ion beam and directing the produced ion beam to thevariable aperture; shaping the ion beam using the variable aperture toform a first shaped ion beam having the first ion beam parameter andapplying the first shaped ion beam to the first portion of thesubstrate; and shaping the ion beam using the variable aperture to forma second ion beam having the second ion beam parameter and applying thesecond ion beam to the second portion of the substrate.
 2. The method ofclaim 1, wherein the first shaped ion beam is different in size from thesecond shaped ion beam.
 3. The method of claim 1, wherein the firstportion of the substrate and the second portion of the substrate havedifferent etching rates due to their corresponding properties, andwherein the first shaped ion beam is smaller in size than the secondshaped ion beam.
 4. The method of claim 1, wherein the first portion ofthe substrate and the second portion of the substrate have differentetching rates due to their corresponding properties, and wherein thefirst shaped ion beam is larger in size than the second shaped ion beam.5. The method of claim 4, wherein the first shaped ion beam is differentin shape from the second shaped ion beam.
 6. The method of claim 1,wherein the first shaped ion beam and the second shaped ion beam havethe same shape, wherein the first shaped ion beam is applied to thefirst portion for a time duration, and wherein the second shaped ionbeam is applied to the second portion for a similar or different timeduration.
 7. The method of claim 6, wherein the first shaped ion beam isdifferent in size from the second shaped ion beam.
 8. The method ofclaim 1, wherein the first portion of the substrate and the secondportion of the substrate have different corresponding etching rates, andwherein the applying of the first shaped ion beam and the applying ofthe second ion beam reduces the difference between the correspondingetching rates.
 9. The method of claim 1, wherein the first portion ofthe substrate and the second portion of the substrate have the samecorresponding etching rates, and wherein the applying of the firstshaped ion beam and the applying of the second ion beam increases thedifference between the corresponding etching rates.
 10. The method ofclaim 1, wherein the first shaped ion beam parameter relates to an ionbeam current distribution.
 11. The method of claim 1, wherein the ionbeam has an ion beam current distribution that comprises a center regionbetween two outer regions, the method further comprising: wherein theshaping of the ion beam to form the first shaped ion beam comprisesusing the variable aperture to block at least one of the two outerregions from the shaped ion beam.
 12. The method of claim 11, whereinthe second shaped ion beam parameter relates to an ion beam currentdistribution.
 13. The method of claim 12, wherein the shaping of the ionbeam to form the second shaped ion beam comprises using the variableaperture to block at least one of the two out regions from the shapedion beam.
 14. The method of claim 1, wherein the shaping of the ion beamto form the first shaped ion beam comprises changing the size of across-section of the ion beam.
 15. The method of claim 14, wherein theshaping of the ion beam to form the second shaped ion beam compriseschanging the size of a cross-section of the ion beam.
 16. The method ofclaim 1, wherein the shaping of the ion beam to form the first shapedion beam comprises changing the shape of a cross-section of the ionbeam.
 17. The method of claim 16, wherein the shaping of the ion beam toform the second shaped ion beam comprises changing the shape of across-section of the ion beam.
 18. The method of claim 1, wherein thefirst portion of the substrate has a set of uniform properties and thesecond portion of the substrate has a different set of uniformproperties.
 19. The method of claim 1, wherein the first portion of thesubstrate has a first set of non-uniform properties and the secondportion of the substrate has a second set of non-uniform properties,wherein the first and second set of non-uniform properties are notidentical.